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Aljoufi A, Zhang C, Ropa J, Chang W, Palam LR, Cooper S, Ramdas B, Capitano ML, Broxmeyer HE, Kapur R. Physioxia-induced downregulation of Tet2 in hematopoietic stem cells contributes to enhanced self-renewal. Blood 2022; 140:1263-1277. [PMID: 35772013 PMCID: PMC9479026 DOI: 10.1182/blood.2022015499] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 06/17/2022] [Indexed: 12/15/2022] Open
Abstract
Hematopoietic stem cells (HSCs) manifest impaired recovery and self-renewal with a concomitant increase in differentiation when exposed to ambient air as opposed to physioxia. Mechanism(s) behind this distinction are poorly understood but have the potential to improve stem cell transplantation. Single-cell RNA sequencing of HSCs in physioxia revealed upregulation of HSC self-renewal genes and downregulation of genes involved in inflammatory pathways and HSC differentiation. HSCs under physioxia also exhibited downregulation of the epigenetic modifier Tet2. Tet2 is α-ketoglutarate, iron- and oxygen-dependent dioxygenase that converts 5-methylcytosine to 5-hydroxymethylcytosine, thereby promoting active transcription. We evaluated whether loss of Tet2 affects the number and function of HSCs and hematopoietic progenitor cells (HPCs) under physioxia and ambient air. In contrast to wild-type HSCs (WT HSCs), a complete nonresponsiveness of Tet2-/- HSCs and HPCs to changes in oxygen tension was observed. Unlike WT HSCs, Tet2-/- HSCs and HPCs exhibited similar numbers and function in either physioxia or ambient air. The lack of response to changes in oxygen tension in Tet2-/- HSCs was associated with similar changes in self-renewal and quiescence genes among WT HSC-physioxia, Tet2-/- HSC-physioxia and Tet2-/- HSC-air. We define a novel molecular program involving Tet2 in regulating HSCs under physioxia.
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Affiliation(s)
| | - Chi Zhang
- Department of Medical and Molecular Genetics, and
| | - James Ropa
- Department of Microbiology and Immunology
| | - Wennan Chang
- Department of Medical and Molecular Genetics, and
| | - Lakshmi Reddy Palam
- Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN
| | | | - Baskar Ramdas
- Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN
| | | | | | - Reuben Kapur
- Department of Microbiology and Immunology
- Herman B Wells Center for Pediatric Research, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN
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2
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Zhang H, Hudson FZ, Xu Z, Tritz R, Rojas M, Patel C, Haigh SB, Bordán Z, Ingram DA, Fulton DJ, Weintraub NL, Caldwell RB, Stansfield BK. Neurofibromin Deficiency Induces Endothelial Cell Proliferation and Retinal Neovascularization. Invest Ophthalmol Vis Sci 2019; 59:2520-2528. [PMID: 29847659 PMCID: PMC5963003 DOI: 10.1167/iovs.17-22588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Purpose Neurofibromatosis type 1 (NF1) is the result of inherited mutations in the NF1 tumor suppressor gene, which encodes the protein neurofibromin. Eye manifestations are common in NF1 with recent reports describing a vascular dysplasia in the retina and choroid. Common features of NF1 retinopathy include tortuous and dilated feeder vessels that terminate in capillary tufts, increased endothelial permeability, and neovascularization. Given the retinal vascular phenotype observed in persons with NF1, we hypothesize that preserving neurofibromin may be a novel strategy to control pathologic retinal neovascularization. Methods Nf1 expression in human endothelial cells (EC) was reduced using small hairpin (sh) RNA and EC proliferation, migration, and capacity to form vessel-like networks were assessed in response to VEGF and hypoxia. Wild-type (WT), Nf1 heterozygous (Nf1+/−), and Nf1flox/+;Tie2cre pups were subjected to hyperoxia/hypoxia using the oxygen-induced retinopathy model. Retinas were analyzed quantitatively for extent of retinal vessel dropout, neovascularization, and capillary branching. Results Neurofibromin expression was suppressed in response to VEGF, which corresponded with activation of Mek-Erk and PI3-K-Akt signaling. Neurofibromin-deficient EC exhibited enhanced proliferation and network formation in response to VEGF and hypoxia via an Akt-dependent mechanism. In response to hyperoxia/hypoxia, Nf1+/− retinas exhibited increased vessel dropout and neovascularization when compared with WT retinas. Neovascularization was similar between Nf1+/− and Nf1flox/+;Tie2cre retinas, but capillary drop out in Nf1flox/+;Tie2cre retinas was significantly reduced when compared with Nf1+/− retinas. Conclusions These data suggest that neurofibromin expression is essential for controlling endothelial cell proliferation and retinal neovascularization and therapies targeting neurofibromin-deficient EC may be beneficial.
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Affiliation(s)
- Hanfang Zhang
- Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, Georgia, United States.,Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - Farlyn Z Hudson
- Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, Georgia, United States.,Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - Zhimin Xu
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - Rebekah Tritz
- Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, Georgia, United States.,Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - Modesto Rojas
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States.,Department of Pharmacology and Toxicology, Augusta University, Augusta, Georgia, United States
| | - Chintan Patel
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - Stephen B Haigh
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - Zsuzsanna Bordán
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States
| | - David A Ingram
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana, United States.,Department of Neonatal-Perinatal Medicine, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - David J Fulton
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States.,Department of Pharmacology and Toxicology, Augusta University, Augusta, Georgia, United States
| | - Neal L Weintraub
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States.,Department of Cardiology, Augusta University, Augusta, Georgia, United States
| | - Ruth B Caldwell
- Vascular Biology Center, Augusta University, Augusta, Georgia, United States.,Vision Discovery Institute, Augusta University, Augusta, Georgia, United States.,Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, United States.,Charlie Norwood VA Medical Center, Augusta, Georgia, United States
| | - Brian K Stansfield
- Department of Pediatrics and Neonatal-Perinatal Medicine, Augusta University, Augusta, Georgia, United States.,Vascular Biology Center, Augusta University, Augusta, Georgia, United States.,Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
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3
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Rognlien AGW, Wollen EJ, Atneosen-Åsegg M, Saugstad OD. Increased expression of inflammatory genes in the neonatal mouse brain after hyperoxic reoxygenation. Pediatr Res 2015; 77:326-33. [PMID: 25423075 DOI: 10.1038/pr.2014.193] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 09/05/2014] [Indexed: 11/09/2022]
Abstract
BACKGROUND Hyperoxic reoxygenation following hypoxia increases the expression of inflammatory genes in the neonatal mouse brain. We have therefore compared the temporal profile of 44 a priori selected genes after hypoxia and hyperoxic or normoxic reoxygenation. METHODS Postnatal day 7 mice were subjected to 2 h of hypoxia (8% O2) and 30 min reoxygenation with 60% or 21% O2. After 0 to 72 h observation, mRNA and protein were examined in the hippocampus and striatum. RESULTS There were significantly higher gene expression changes in six genes after hyperoxic compared to normoxic reoxygenation. Three genes had a generally higher expression throughout the observation period: the inflammatory genes Hmox1 (mean difference: 0.52, 95% confidence interval (CI): 0.15-1.01) and Tgfb1 (mean difference: 0.099, CI: 0.003-0.194), and the transcription factor Nfkb1 (mean difference: 0.049, CI: 0.011-0.087). The inflammatory genes Cxcl10 and Il1b, and the DNA repair gene Neil3, had a higher gene expression change after hyperoxic reoxygenation at one time point only. Nineteen genes involved in inflammation, transcription regulation, apoptosis, angiogenesis, and glucose transport had significantly different gene expression changes with time in all intervention animals. CONCLUSION We confirm that hyperoxic reoxygenation induces a stronger inflammatory gene response than reoxygenation with air.
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Affiliation(s)
- Anne Gro W Rognlien
- Department of Pediatric Research, University of Oslo, Oslo University Hospital HF, Oslo, Norway
| | - Embjørg J Wollen
- Department of Pediatric Research, University of Oslo, Oslo University Hospital HF, Oslo, Norway
| | - Monica Atneosen-Åsegg
- 1] Department of Pediatric Research, University of Oslo, Oslo University Hospital HF, Oslo, Norway [2] Department of Clinical Molecular Biology and Laboratory Sciences, Akershus University Hospital, Lørenskog, Norway
| | - Ola Didrik Saugstad
- Department of Pediatric Research, University of Oslo, Oslo University Hospital HF, Oslo, Norway
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